A mechanic clockwork has as central components a mainspring barrel, a gear train, an escapement and an oscillator (balance wheel). Thereby the barrel with the mainspring provides the drive of the clockwork. Transferring the force occurs beginning at the mainspring barrel, via the movement to the escape wheel, which constitutes a component of the escapement. The movement drives the hands of the clock and transmits the spring force, which is stored in the mainspring, into rotations with different velocities, by what seconds, minutes, hours and so on are indicated.
U.S. Pat. No. 3,903,686 reveals a chronograph with a second hand, a minute hand and an hour hand, wherein these hands are combined with a minute- and second counter and possess the characteristic, that the second hand, the minute counter and the hour counter can be positioned to zero.
The German translation DE 698 30 930 T2 of the European patent EP 1 046 970 B1 reveals an intermittent feeding mechanism, by which a feeding latch is mounted on a first counting wheel with a part of a spring. The feeding latch rotates together with a first counting wheel, so that each turnaround of the feeding latch catches a gear of a second counting wheel or a second intermediate counting wheel, whereby the second counting wheel or the second intermediate counting wheel is pushed forward in an intermittent manner. This intermittent feeding mechanism has a protruding part mounted on the feeding latch, whereby a positioning hole is provided in a component of the first counting wheel. When the protruding part is inserted into the positioning hole and the protruding part is drifted through a part of the spring of the feeding latch, a positioning of the feeding latch occurs.
The escapement wheel represents the connection between the gear train and balance wheel of the clockwork. The balance wheel comprises an oscillating body, which is mounted in a rotatable manner around an axis of rotation by means of a balance wheel shaft. In addition a spiral spring is provided, which forms the oscillatory and clocking system together with the mass of the oscillating body. Finally the balance wheel comprises a device for regulating gears as for example a jiggler, with which the characteristics of the oscillation of the spiral spring can be changed and therefore the desired correct rate of the watch can be set. The proper rate of the watch is based on a preferably steady bidirectional oscillation of the balance wheel. Without delivering energy permanently, the balance wheel would however stop its movement. That is why the force, coming from the mainspring barrel, is transmitted continuously via the gear train to the balance wheel. The escapement transfers the force via escapement wheel and tie bar to the balance wheel. Thereby the tie bar engages alternately in a retardant and released manner into the escaping wheel that the movement always pulses in the same tempo.
Thereby, depending on the oscillation frequency of the balance wheel, an exact basic time unit is determined, on which the remaining arithmetic of the transferring wheels and therefore the accuracy of the clock is based. The exactness of the measurements of a mechanic chronograph also depends completely directly on this unit, since the chronograph is usually driven by the movement of the clock.
A chronograph, as for example the clockwork of type ETA Valjoux 7750, has at least a second hand and a minute hand, which can be stopped, reset to zero and started again on demand. The display of the measured time interval by means of a chronograph, can occur thereby by separate second- and minute dials or by a second hand and a minute hand, disposed coaxially with the original hands of the clock. In case of coaxially disposed hands, it is called a center second hand and a center minute hand.
The drive of the chronograph, which is shown in FIG. 1 and known from the prior art, occurs via a swiveling drive (not shown), which forces the gear train of the clock to engage with the second wheel 3. The pulse-receiving wheel 6 and the drive wheel 7, which is coaxially disposed above and rigidly connected to the pulse-receiving wheel 6, are suspended and are rigidly connected to a shaft (not shown), which is in turn is rotatable mounted in a plate disposed above the drive wheel 7.
The entraining spring 5 is rigidly connected to the second wheel 3 with its section averted from the pulse-receiving wheel 6. The section of the entraining spring 5, which is turned towards the pulse-receiving wheel 6, is developed resilient and provided for engagement into the pulse-receiving wheel 6.
The zeroing shaft 11 is rigidly connected to the zeroing wheel 8. The zeroing shaft 11 bears at its end, averted to the zeroing wheel 8, the intermediate wheel 15, which is in constant engagement with the pulse-transmitting wheel 9, which is in turn in constant engagement with the minute wheel 10. After a complete rotation of the second wheel 3, so after 60 seconds, the pulse-receiving wheel 6 is rotated for 6° by the entraining spring 5. The zeroing wheel 8, the intermediate wheel 15, the pulse-transmitting wheel 9 and the minute wheel 10 are moved further by means of the drive wheel 7, by what the center minute hand 2, which is rigidly connected to the minute wheel 10, finally advances for one unit.
The center second hand 1 is rigidly connected to the second shaft 4, which is in turn rigidly connected to the second wheel 3. The second shaft 4 penetrates the center of the minute wheel 10. The slewing drive (not shown) provides a direct drive of the second hand 3, whereby the center second hand 1 is moved via the second shaft 4.
A further component of the chronograph is the two-part developed zeroing lever 12, comprising a zeroing lever arm 12a and a zeroing interlock 12b (not visible in FIG. 1), wherein the zeroing lever 12 is stored in a rotatable manner around the pivotal point of the zeroing lever arm 19. The zeroing lever interlock 12b (see FIG. 3) is in turn connected in a rotatable manner around the pivotal point of the zeroing lever interlock to the zeroing lever arm 12a. The zeroing lever arm 12b is located in one plane with the zeroing heart for minutes 17 and the zeroing heart for seconds 16. The zeroing heart for minutes 17 is rigidly connected to the zeroing wheel 8 via the zeroing shaft 11, whereas the zeroing heart for seconds 16 is rigidly connected to the second wheel 3 via the second shaft 4.
For stopping the chronograph, the slewing drive (not shown) is forced to release its engagement with the second wheel 3 with the help of a pusher (not shown). In addition, operating the pusher occurs in forcing an appropriate holding means (not shown), as for example a blocking interlock, to engage with the second wheel 3. Operating the pusher therefore results in a halt of center second hand 1 and center minute hand 2.
For bringing the chronograph into its zero position for a further measurement of time, the blocking interlock (not shown) is forced to release its engagement with the second wheel 3 by means of a further pusher. Simultaneously, by operating the pusher, the zeroing lever arm 12a and therefore the zeroing lever interlock 12b, as well, are pivoted for a small value in their corresponding plane, whereby the zeroing lever interlock 12b contacts with its front the zeroing heart for minutes 17 as well as the zeroing heart for seconds 16. Therefore the zeroing heart for minutes 17 and the zeroing wheel 8, which is rigidly connected to the zeroing heart 17 via the zeroing shaft 11, as well as the zeroing heart for seconds 16 and the second wheel 3, which is rigidly connected to the zeroing heart 16 via the second shaft 4, are rotated so far until they are located in their zero position. This is the case, if the first angled end 13 of the zeroing lever interlock 12b touches the flattened end 17′ of the zeroing heart for minutes 17 and the second angled end 14 of the zero lever interlock 12b touches the flattened end 16′ of the zeroing heart for seconds 16.
Due to the movement of the zeroing wheel 8 in its zero position, the intermediate wheel 15, the pulse-transmitting wheel 9, the minute wheel 10 and the center minute hand 2 are moved to their particular zero position, as well. Analogous to that due to the movement of the second wheel 3 to its zero position, the center second hand 1 is moved to its zero position, as well.